Books seem to go incredibly cheap on Amazon and Ebay, with people selling them for a few cents a lot of the time, and some misjudged shipping means you could be paying for it instead of getting anything. Research what each book is going for to decide.
The books I had just weren't worth the trouble, so I gathered them in a big box and dropped it in the library's donation cart. From perusing their stuff previously, I noticed their dearth of sci-fi novels, so I remedied the problem.